Antenna #13. How to Calculate the Receiver Power, Pr. How Antenna Noise Temp Affects the Rx Pwr. скачать в хорошем качестве

Antenna #13. How to Calculate the Receiver Power, Pr. How Antenna Noise Temp Affects the Rx Pwr.

Antenna Design playlist.    • Antenna #1. Types of Antennae: Loop, Dipol...   For access to this presentation materials, membership is required: I need the Material PPT Sent me an email to Technologies.Discussion@gmail.com If you need the whole playlist material, send me email and we discuss. Give me some time to response. Thanks. How to Determine the Noise Floor by Calculate Antenna Noise Temperature Pr = k TA B How to Calculate Receive Power (Proportional to Antenna Environment Temperature). How to Calculate Received Power by Understand the Effect of Antenna Temperature. Antenna Temperature is a measure of the noise generated by an antenna in a given environment, also referred to as Antenna Noise Temperature. This is not the physical temperature of the antenna itself; rather, it depends on the antenna's gain, radiation pattern and the noise picked up from the surrounding environment. To define the environment (and thus provide a complete definition of antenna temperature), we will introduce a temperature distribution, which represents the temperature in every direction away from the antenna in spherical coordinates. For example, the temperature of the night sky is approximately 4 Kelvin, while the temperature in the direction of the Earth's surface corresponds to the physical temperature of the ground. This equation shows that the antenna temperature is calculated by integrating over the entire sphere, based on the radiation pattern of the antenna and the temperature distribution of the antenna. This states that the temperature surrounding the antenna is integrated over the entire sphere and weighted by the antenna's radiation pattern. Thus, an isotropic antenna would have a noise temperature that represents the average of all temperatures around it. For a perfectly directional antenna (such as one with a pencil beam), the antenna temperature will depend only on the temperature in the direction it is "pointing." Consequently, an antenna's temperature will vary depending on whether it is directional and aimed into space or directed toward the sun. Here’s how antenna temperature works and is calculated: Measurement in Kelvin: Antenna temperature is usually measured in Kelvin (K), where a higher temperature indicates more power from the radiation field being received. Power Relation: The antenna temperature (Ta​) is proportional to the power density received by the antenna. The total received power Pr​ is calculated as: Pr = k TA B where: k is the Boltzmann constant, k = 1.38 X 10-23 J/K TA​ is the antenna temperature in Kelvin, B is the bandwidth in Hz. The receiver has a temperature TR & total system temperature (antenna plus receiver) has a combined temperature given by Tsys = TA + TR. A parameter often encountered in antenna specification sheets for operation in certain environments is the ratio of the antenna gain to the antenna temperature (or system temperature, if a receiver is specified). This parameter is denoted as G/T and has units of dB/Kelvin [dB/K]. Additionally, many RF engineers use the term Noise Figure (or Noise Factor, NF) to describe system performance. Noise Figure is the ratio of the input SNR (signal-to-noise ratio) to the output SNR. Essentially, all RF devices (such as mixers and amplifiers) introduce some noise. However, antenna temperature is not directly related to Noise Figure, as the power level of the signal input can vary significantly depending on the desired signal's direction of arrival, while the noise contribution remains constant. In summary, antenna temperature is a key concept in understanding the amount of radiation an antenna receives, which can represent either signal or noise, depending on the application. It helps quantify the effective power of this radiation by linking it to the temperature concept, facilitating better analysis and system design in both astronomy and communications.